Core i7-8700 vs 8700K: How fast the non-K SKU runs depends on This

Wondering how fast is the Core i7-8700 Coffee Lake? Tests show that depends entirely on the platform. When left free, the processor performs on par with the flagship i7-8700K. If the OEM slows down however, the clock speeds and power drop significantly—somehow based on the TDP spec.

It’s about the difference in TDP, at least on paper

Intel Ark details the difference in the TDP and clock frequencies of the Core i7-8700 vs 8700K as: 30W TDP, 500 MHz base clock, and 100 MHz max clock per core. The TDP side of things change under load with the non-K package requires 130W instead of 65W.

Intel defines TDP as “the average power, in watts, the processor dissipates when operating at Base Frequency with all cores active under an Intel-defined, high-complexity workload.” In other applications and at different clock rates, the power consumption may differ. There is no clear indication about the consumption of the CPU within the given clock margins.

Recently, Intel declared it will no longer officially disclose its per-core turbo frequencies. The company will only specify processor frequencies for base and single-core Turbo in its processor marketing and technical collateral. ComputerBase has, however, determined per-core turbo for both processors. The results show that 2- and 4-core turbo continue to differ by 100 MHz, whereas the all 6-core turbo is the same.

Intel Core i7-8700 vs 8700K: Performance on par, but Not Always

Now when tested on the Gigabyte Aorus Z370 Gaming Ultra motherboard, both Core i7-8700 and i7-8700K ran at the same max turbo clock of 4.3 GHz in all scenarios (without using the board’s Auto-OC functionalities). The power consumption remained the same as well. This means both processors were on par with each other in all applications tested.

ComputerBase also tested the 8th Gen CPUs in the ALDI Medion Erazer X67015 gaming PC. There was no difference in performance in games with comparatively low CPU load, but that wasn’t the case with applications. The Core i7-8700 performed 7-19% lower compared to its elder sibling on all-core turbo.

As for the reason, it was identified that after 15 seconds of load, the clock rates of the CPU dropped sharply from 4.3 GHz to 3.6 GHz. HWiNFO showed power consumption to be only 65 watts.

Medion referred to the official Intel spec for the 65W TDP, though it did acknowledge that there are some gaming motherboards with a Z370 chipset that can deliver higher TDP. As a result, the CPU will then achieve higher clock rates, but will operate outside of its specification.

Intel explained this in a statement (machine-translated from German):

Focusing on Cinebench as a diagnostic, the correct score for i7-8700 should be about 1383. We recommend watching the CPU frequencies by using CPU-Z or HWinfo during the Cinebench run. The 65W TDP limit is meant to kick in after several seconds for Cinebench. For the first several seconds it will run at max all-core turbo (4.3 GHz on i7-8700). After approximately 8 seconds it will drop to 4.1 GHz or 4.2 GHz. This is the 65W limit taking effect. Exact performance numbers could be related to OEM configurations.

According to Intel, the Core i7-8700 scores 1383 points in the Cinebench R15. This is exactly what ComputerBase achieved when it performed tests on the Gigabyte Aorus Z370 Gaming Ultra.

The CPU is expected to hit a max turbo clock of 4.3 GHz on all 6 cores, but after about eight seconds, it drops slightly to 4.1 to 4.2 GHz. This is when the “65W TDP limit” comes into effect.

For Medion, it seems that the effect brakes the processor hard. It takes 15 seconds instead of 8 before the TDP limit hits, after which the turbo clock falls to 3.6 to 3.7 GHz. Nevertheless, Intel doesn’t deem the Erazer X67015 behaviour to be wrong. After all, limiting a CPU to 65W TDP after a short boost is obviously compliant with specifications.

What’s your take on this? Tell us in the comments below.